Alerting all Shanghailanders! The local watchdog has found that seafood hawkers in Hongkou and Baoshan districts are using oxalate, a banned substance known to cause kidney stones, to clean their wares. Unfortunately, perpetrators have so far managed give authorities the “slip.” ECNS reports:

The announcement was made following visits to four wet markets in Hongkou and Baoshan districts last week, where two stalls were found to be using the banned substance oxalate as a cleaning agent, the Shanghai Food and Drug Administration said.The use of oxalate is prohibited under food safety law, and violators can face criminal charges, the agency said on its website.Vendors use oxalate for cleaning eels because it is a cheap alternative to vinegar. But if consumed in large quantities it can cause medical problems such as kidney stones.